Perfluoroalkyl phosphonates

ABSTRACT

PERFLUOROZLKYL IODIDE MONOMER AND TELOMER ESTER ADDUCTS OF DIETHYL V INYLPHOSPHONATE WERE PREPARED BY FREE RADICAL ADDITION. IODINE OF THESE ADDUCTS WAS REPLACED BY HYDROGEN, AND DERIVATIVES OF THE REDUCED PHOSPHONATE ADDUCTS WERE PREPARED, WHICH INCLUDE PHOSPHONIC ACIDS, ACID CHLORIDES, AND AZIRIDINYL PHOSPHINE OXIDES. THE AZIRIDINYL PHOSPHINE OXIDES ARE USED TO IMPART OIL AND WATER REPELLENCY TO CELLULOSIC TEXTILES. THE OTHER DERIVATIVES ARE USEFUL AS CHEMICAL INTERMEDIATES AS WELL AS POTENTIAL FOAMING AGENTS.

United States Patent 3,763,282 PERFLUOROALKYL PHOSPHONATES Leon H.Chance and Jerry P. Moreau, New Orleans, La., assignors to the UnitedStates of America as represented by the Secretary of Agriculture NoDrawing. Original application July 18, 1969, Ser. No. 843,200, nowPatent No. 3,639,144. Divided and this application June 9, 1971, Ser.No. 151,558

Int. Cl. C07f 9/40 US. Cl. 260932 3 Claims ABSTRACT OF THE DISCLOSUREPerfluoroalkyl iodide monomer and telomer ester adducts of diethylvinylphosphonate were prepared by free radical addition. Iodine of theseadducts was replaced by hydrogen, and derivatives of the reducedphosphonate adducts were prepared, which include phosphonic acids, acidchlorides, and aziridinyl phosphine oxides. The aziridinyl phosphineoxides are used to impart oil and water repellency to cellulosictextiles. The other derivatives are useful as chemical intermediates aswell as potential foaming agents.

This application is a division of application bearing Ser. No. 843,200,filed July 18, 1969, now Pat. No. 3,639,144.

A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to perfluoroalkyl adducts of diethylvinylphosphonate, to derivatives thereof, to the preparation thereof,and to processes for imparting improved properties to cellulosictextiles by treating said textiles with certain of the perfluoroalkylphosphorus derivatives of this invention. More specifically, thisinvention relates to the preparation of perfluoroalkyl phosphonateesters and to the corresponding acids, acid chlorides, and aziridinylderivatives, useful in oil and water repellent finishes for textiles andalso useful as chemical intermediates and potential foaming agents.

DEFINITION (1) Telomers are polymers of low molecular weight such as areencountered, for example, in the free-radical addition of an addendum XYto ethylene, which may be represented as where n is small; the processis known as telomerization. Kingzetts Chemical Encyclopedia, 9th ed.

(2) Telomerization does not differ essentially from other polymerizationcatalyzed by free radicals. It arises merely because enough of asufiiciently reactive compound is present to act as a chain transferreagent, but the concentration and reactivity are not high enough togive rise chiefly to 1,2, addition. Carl R. Nollers Chemistry of OrganicCompounds.

The main object of the instant invention is to disclose new phosphoniccompounds containing a perfiuoroalkyl radical connected to thephosphorus atom by an ethylene (-CH CH linkage.

A second object of the instant invention is to provide methods ofpreparing new perfluoroalkyl phosphonic compounds.

A third object of the instant invention is to provide a process forimparting to cotton and other cellulosic materials both oil and waterrepellency using some of the new compounds of the instant invention.

lCC

A forth object of the invention is to provide a process for imparting tocotton and other cellulosic textiles resistance to soiling and staining.

Searching the prior art we find that a dialkyl phosphonate reacts withtetrafiuoroethylene in a pressure vessel using a free radical initiatorto produce products of the general formula H(CF CH ,PO(OR) [Neal D.Brace, J. Org. Chem. 26, 3197 (1961).] These products have a terminalhydrogen atom on the perfiuoro group, and consequently are not aseffective in producing oil and water repellency as similar products inwhich the terminal hydrogen is replaced by a fluorine atom.

One improvement which is a facet of the present invention over the priorart is this. We have found that compounds of the present inventionimpart excellent oil repellency and moderate water repellency tocellulosic materials because the perfiuoro group has a terminal CF groupinstead of a terminal HCF group.

In the course of investigation we have found that compounds of thegeneral formula wherein n is an integer from 1 to 10, R is an alkylradical, and y is an integer from 1 to 3 can be prepared by reacting aperfiuoroalkyl iodide with a dialkyl vinylphosphonate in the presence ofa free radical catalyst.

We have also found that a series of reactions can be carried outbeginning with compounds represented by graphic Formula A to produceproducts represented by the following equations:

CHg-CH -l where n is an integer from 1 to 10, and y is an integer from 1to 3.

In accordance with the present invention the reaction of the dialkylvinylphosphonate with the perfluoroalkyl iodide is carried out byheating in the presence of a selected catalyst. Typical catalystssuitable for the reaction are organic peroxides, such as di-, tert-,butyl peroxide or azobisnitriles such as azobis(isobutyronitrile). Twomain products are obtained from this type reaction and include themonomeric perfluoroalkyl iodide adduct and a telomer in which thedialkyl phosphonate moiety is dimeric. A mixture of unidentified highermolecular weight telomers are also obtained. Typical examples arerepresented by the reaction of diethyl vinylph'osphonate andperfiuorohepyl iodide to give a monomeric phosphonate ester of theformula C F CI-I CH (I)P(O) (OC H and a telomer ester of the formula(CQH50)3P(O)CHCH2CH(I)P (0) (0 0,11,),

CH2C7F15 Also in accordance with the present invention the iodine atomis removed from the perfluoroalkyl phosphonate esters by a reducingagent, and replaced by a hydrogen atom. The preferred reducing agent iszinc metal and hydrochloric acid. Typical reduced phosphonate esters arerepresented by a monomer of the formula and a telomer of the formula (025 (O) CHCH2CH2P C2135):

OHzC1F1n The conversion of the reduced phosphonate esters to thephosphonic acids is carried out by hydrolysis in the presence of amineral acid. The preferred acid is hydrochloric acid. The conversion ofthe phosphonic acids to the phosphonic dichloride is carried out byheating With PCl in a suitable solvent. The preferred solvent is carbontetrachloride.

The conversion of the phosphonic dichloride to the diaziridinylderivative is carried out by reaction with aziridine in a suitableorganic solvent in the presence of an acid acceptor. A variety ofsolvents are suitable and include benzene and chlorinated solvents suchas carbon tetrachloride or methylene chloride. Suitable acid acceptorsinclude tertiary organic bases such as triethylamine and inorganic basessuch as sodium or potassium hydroxide. The preferred base istriethylamine. Typical diaziridinyl derivatives are represented by amonomer of the formula and a telomer of the formula (CHqCHmNhP (o) CHCHCH P (o) (NCH7CH:)3

Each of the new type perfluoroalkyl phosphonic compounds mentioned aboveis useful as a precursor to the type compound which follows. Finally,the aziridinyl derivatives are useful as oil and water repellents fortextiles, particularly for cotton or other cellulosic textiles, and forpaper. The phosphonic acid derivatives have use as potential foamingagents.

The perfluoroalkyl aziridinyl phosphine oxide can be applied tocellulosic materials from a variety of solvents. Suitable solvents arewater, alcohols such as ethanol or methanol and glycol ethers such asethylene glycol monoethyl ether. The preferred solvent is water. Thepreferred concentration of the phosphine oxides used in the solutionsdepends on the particular phosphine oxide being used and on the degreeof oil and water repellency desired, and may vary about from 3% to 10%by weight of the total solution. Aqueous solutions are preferred.

Polymerization of the phosphine oxides on the cellulosic material iscarried out in the presence of latent acid catalysts such as magnesiumchloride, zinc nitrate, or zinc fluoborate. The catalyst concentrationmay vary about from 0.5% to 2% by weight of the total solution, thepreferred concentration depending on the concentration of the phosphineoxide.

The polymerization on cellulosic materials may be carried out byimpregnating the cellulosic material with a solution of the phosphineoxide and catalyst, drying, and curing at temperatures ranging aboutfrom 120 C. to 160 C. for periods of time about from 3 minutes to 30minutes, the longer times being used with the lower temperatures.

Cotton fabrics which have been treated by the processes of thisinvention are tested for oil repellency, water repellency, and drycleaning durability by AATCC Standard Method No. 118-1966T, 22-1964, and86-1963T, respectively. These tests are recommended by the AmericanAssociation of Textile Chemists and Colorists. Laundering durabilitytests on the cotton fabrics are performed in an automatic home-typewashing machine using a detergent, followed by a 50 minute drying cyclein a tumble dryer. Screening laundry tests were carried out in aTergitometer using a detergent.

The following examples illustrate procedures that have been successfullyused in carrying out the invention and are not meant as a limitationthereof.

PREPARATION OF PERFLUOROALKYLPHOS- PHONIC COMPOUNDS Example 1 Diethyll-iodo-lH, ZH-perfluorononylphosphonate (Ia) and tetraethyl 1 (1H,1Hperfluorooctyl)-3-iodo-1,3-trimethylenediphosphonate(Ib).-Diethylvinylphosphonate (57.8 g., 0.35 mole) and perfluoroheptyliodide (192.1 g., 0.39 mole) were placed into a 3-neck r.b. flaskequipped with a magnetic stirrer, thermometer, gas inlet tube, andcondenser connected to a mercury air trap. Light was excluded bycovering the flask With aluminum foil. Azobis- (isobutyronitrile)catalyst (1.15 g., 0.007 mole) was added and the system flushed withnitrogen. The flask was heated in a water bath to at which temperaturean exothermic reaction began. An ice bath was used to keep thetemperature below 150. Reaction temperature was then maintained atapproximately for 6 hours. Unreacted material g.) was removed by vacuumdistillation below 50 (0.3 mm.). The residue (153.1 g.) was crude mixediodo-esters (I). A small amount of I was distilled under vacuum. Theiodo-adduct (Ia) had B.P. 108-114 (0.03 mm); 21 1.3930.

Analysis.-Calcd. for C H F IO (percent): C, 23.65; H, 1.99; F, 43.17; I,19.22; P, 4.69; mol. wt. 660*. Found (percent): C, 23.81; H, 2.02; F,43.17; I, 19.09; P, 4.90; mol. wt. (benzene), 650.

The iodo-telomer (=Ib) had B.P. 144-6 (0.03 mm.); 11 1.4074.

Analysis.-Calcd. for C H F IO P (percent): C, 27.69; H, 3.18; F, 34.57;I, 15.40; P, 7.52; mol. wt., 824. Found (percent): C, 27.80; H, 3.14; F,34.55; I, 15.18; P, 7.24; mol. wt. (benzene), 830.

Example 2 Diethyl 1'H,1H,2H, 2H-perfiuorononylphosph'onate (11a) andtetraethyl 1-(1H, lH-perfluorotictyD-l,3-trimethylenediphosphonate IIb).

A slurry of 30 g. of zinc dust in 200 ml. of ethanol was heated in awater bath to 60 with stirring. An ethanolic solution of I (153.1 g.)and 75 ml. of conc. hydrochloric acid Were added from separate droppingfunnels within 30 minutes. The bath temperature was raised to 70 then 15g. of Zinc and 40 ml. of hydrochloric acid Were added in increments over1 hour. The mixture Was heated an additional hour at 80, cooled,filtered and concentrated on a rotary evaporator. The concentrate wasWashed with distilled water, then taken up in diethyl ether. The ethersolution was washed with sodium bicarbonate, then with water toneutrality. The ether solution was dried over sodium sulfate, filteredand concentrated on a rotary evaporator. The reduced esters (113 g.,were distilled under vacuum to give 40.9 g. (22% yield from diethylvinyl phosphonate DEVP) of Ila, n 1.3538; 9.3% of intermediate fraction,11 1.3694; 42.3 g. (35% yield from DEVP) of IIb, 11 1.3857; and 14.2 g.of residue. The residue was stirred with absolute ethanol and filteredto give a fine brown solid (unidentified). The filtrate was concentratedto give a dark brown liquid believed to be another telomer, n=3.

'Redistillation of a portion of IIa gave B.P. 82-84 (0.05 mm.).

Analysis.-Calcd. for C H F O P (percent): C, 29.23; H, 2.64; F, 53.35;P, 5.80. Found (percent): C, 29.34; H, 2.84; F, 53.18; P, 5.59.

\IIb had B.P. 138-140 (0.05 mm.).

Analysis-Calcd. for C H F 0 P (percent): C, 32.68; H, 3.90; F, 40.81; P,8.87; mol. wt. 6.98. Found (percent): C, 32.72; H, 4.00; F, 40.88; P,8.69; mol. wt. (chloroform) ,7 02.

Analysis.-Solid residue; I, 28.79; H, 3.36; F, 29.35; P, 10.34.

Analysis-Liquid residue: Calcd. for C H F O P (percent): C, 34.82; H,4.67; F, 33.04; P, 10.77. Found (percent): C, 33.37; H, 4.33; F, 31.34;P, 9.79.

Example 3 1H, 1H, 2H, ZH-perfluorononylphosphonic dichloride (IIIa).-IIa(40 g., 0.075 mole) was heated with 100 ml. of conc. hydrochloric acidat gentle reflux for 3 hours. The mixture was concentrated under vacuumto a gelatinous mass. Conc. hydrochloric acid (75 ml.) was added to themixture and refluxed overnight. The mixture was again concentrated undervacuum. Benzene was added and the remaining water removed by azeotropicdistillation into a Dean-Stark trap. After removal of benzene, the solidresidue was dried under vacuum at 105 C. to a constant weight to givethe crude acid-adduct. This crude acid was dispersed in carbontetrachloride and added to a r.b. flask equipped with a magneticstirrer, condenser and drying tube. The mixture was heated to gentlereflux then phosphorus pentachloride (36.6 g., 0.176 mole) was addedcautiously in small portions through the condenser. The addition wascompleted in 30 minutes, and the solution refluxed overnight. Sulfurdioxide was bubbled through the Warm solution to remove excessphosphorus pentachloride. The solution was concentrated under wateraspirator vacuum, and the residue distilled at 69-72 (0.04 mm.) to givean 83% yield (32.2 g., 0.062 mole) of IIIa, a white solid.

AnaZysis.-Calcd. for C H Cl F OP (percent): C, 20.99; H, 0.78; Cl,13.77; F, 55.34; P, 6.01. Found (percent): C, 20.79; H, 089; C1, 13.76;F, 55.13; P, 5.99.

Example 4 1-(lH,lH-perfluoro6ctyl) 1,3 trimethylenedi-phosphonictetrachloride (IIIb).

IIb (57.8 g., 0.083 mole) was heated at gentle reflux for 6 hours withconc. hydrochloric acid (300 ml.) in a one liter r.b. flask equippedwith a 500 ml. defoarnerbulb and a condenser. The mixture was cooled inthe refrigerator and the liquid decanted from the solid. Morehydrochloric acid was added and the procedure repeated. The gel-likematerial was concentrated in a large evaporating dish on the steam coneusing benzene to remove residual water. The solid residue was driedunder vacuum at 105 to a constant weight to give the crude acidtelomer,which was then reacted with phosphorus pentachloride as described forthe crude acid-adduct above. III!) was distilled at '1256 (0.01 mm.) togive a 40% yield (21.7 g., 0.033 mole) of a slightly yellow solid.

Analysis.-Calcd. for C11H'7C14F15O2P2 (percent): C, 20.02; H, 1.07; Cl,21.49; F, 43.18; P, 9.39; mol. wt. 660. Found (percent): C, 20.16; H,1.14; Cl, 21.54; F, 43.29; P, 9.21; mol. wt. (chloroform), 673.

Example 5 1H,1H,2H,ZH-perfluorononylphosphonic acid (IVa) IIIa (2 g.,0.004 mole) was dissolved in chloroform, then heated with 10 g. of waterin an evaporating dish. Residual water was removed by heating withbenzene to dryness. The waxy solid residue was dried in a vacuum oven at105 to a constant weight to give a 97% yield of IVa, M.P. 155.8.

Analysis.Calcd. for C H F O P (percent): C, 22.61; H, 1.27; F, 59.61; P,6.48; mol. wt., 478. Found (percent): C, 22.33; H, 1.26; F, 59.73; P,6.44; mol. wt. (methanol), 471.

Example 6 1-( 1H, lH-perfluorooctyl) -1,3trimethylenediphosphonic acid(IVb).IVb was prepared from IIIb as described for IVa except it wasdried to constant weight in a vacuum desiccator at room temperature.

Analysis.-Calcd. for C H F O P (percent): C, 22.54; H, 1.89; F, 48.62;P, 10.57. Found (percent): C, 22.75; H, 1.95; F, 48.68; P, 10.77.

Example 7 1H,1H,2H,2H perfluorononylbis(l aziridinyl)phosphine oxide(Va).--Redistilled triethylamine (12.6 g., 0.124 mole) and redistilledaziridine (5.4 g. 0.124 mole) in carbon tetrachloride ml.) was added toa 4-neck r.b. flask equipped with a mechanical stirrer, thermometer,dropping funnel and condenser with drying tube. The flask was cooled to5 in an ice bath. 11111 (29 g., 0.056 mole) in 75 m1. of carbontetrachloride was added from the dropping funnel at such a rate as tokeep the reaction temperature below 10". After the addition, thereaction temperature was allowed to rise to room temperature. Thereaction mixture was heated at 35-40 with stirring for 1 hour. Thecopious white precipitate was removed by vacuum filtration, rinsedthoroughly with carbon tetrachloride and dried to give 14.7 g. (95%yield) of triethylamine hydrochloride. The filtrate was cooled at 0overnight then filtered by gravity through sodium sulfate. The clearfiltrate was concentrated to approximately ml. on a rotary evaporatorbelow 40. The solution was treated with decolorizing carbon and sodiumsulfate then filtered by vacuum through diatomaceous earth. The filtratewas again concentrated to approximately 75 ml. then ml. of petroleumether (30-60) was added. The solution was stored at 20 for 1 hour. Theliquid was decanted through filter paper (filtrate No. 1). The slurry ofwhite precipitate was redissolved in 100 ml. of petroleum ether andstored at 20 overnight. The white Waxy precipitate was filtered byvacuum, washed thoroughly with cold petroleum ether and dried in adesiccator to give 8.9 g. of Va, M.P. 49-50; average aziridinyl assay ofduplicate samples, 99.7%. The concentrated filtrate was diluted withpetroleum ether and a second crop of crystals (10.1 g.) was obtained;M.P. 42-44, average aziridinyl assay of duplicate samples, 97.7%. Thefiltrate was combined with filtrate No. 1 and concentrated to a yellowsolid residue (7.1 g.). The first and second crop of crystals gave a 64%yield of Va.

Analysis.Calcd. for C H F N OP (percent): C, 29.59; H, 2.29; F, 53.95;N, 5.30; P, 5.86; mol. wt., 528. Found (percent): C, 29.50; H, 2.41; F,54.00; N, 5.33; P, 5.78; mol. wt. (methanol), 530.

Example 8 1(1H,1H perfluorooctyl) 1,3 trimethylenebis[di(aziridinyl)phosphine oxide] (Vb).Vb was prepared from IVb as describedfor Va to give a 64% yield; M.P. 103107; aziridinyl assay 97.3%. (Vb wasobtained as a slightly purer product when dissolved in carbontetrachloride and a polymeric material removed by filtration; aziridinylassay, 100.2%

Analysis.Calcd. for C H F N O P (percent): C, 33.25; H, 3.38; F, 41.52;N, 8.16; P, 9.03; mol. wt., 686. Found (percent): C, 33.07; H, 3.14; F,41.42; N, 8.08; P, 9.15; mol. wt. (chloroform), 691.

APPLICATION TO COTTON FABRIC In all of the following examples cottonprintcloth was used. In some cases the cloth contained the wash-Wearfinish, dimethylol ethylene urea. The printcloth was immersed in thesolution and the excess squeezed out by passing through squeeze rolls toa wet pickup of 80-83%. The fabric was then dried and cured in a forceddraft oven, and finally rinsed and dried.

The two compounds used in the following examples are1H,lH,2H,2H-perfluorononylbis(1 aziridinyl)phosphine oxide and.1-(1H,lH-perfluorooctyl)-1,3-trimethylene-bis [di(1-aziridinyl)phosphineoxide]. For brevity the two compounds will be designated FNAPO andtelomer, respectively. The term oil rating will be abbreviated OR.

Example 9 A solution was prepared by dissolving FNAPO (0.5 grams) in acombination of water (4.5 grams) and ethanol (5.0 grams). The solutioncontained FNAPO by weight. A sample of printcloth was immersed in 1%aqueous zinc fiuoborate, the excess squeezed out, and the fabric dried.The thus impregnated fabric was then impregnated with the FNAPOsolution, dried for 30 minutes at room temperature and cured for 20minutes at 120 C. The fabric had an oil rating (OR) of 5. The fabric hadan OR of 2 after five laundering cycles and an OR of 5 after 3 hoursextraction with tetrachloroethylene in a Soxhlet extractor.

Example Printcloth was treated as in Example 9 except that the solventwas ethanol instead of water-ethanol and the fabric was cured for 5minutes at 150 C. The OR of the fabric was 6. After 5 launderings the ORwas 2.

Example 11 Printcloth was treated as in Example 9 except that thesolvent was ethylene glycol monoethyl ether, and 2% zinc fluoborate wasused, and the fabric was dried for 3 minutes at 80 C. The OR of thefabric was 6. After 5 launderings the OR was 3.

'Example 12 A 5% aqueous solution of FNAPO containing 1% zinc fluoboratewas prepared and applied to cotton printcloth from a single bath. Thecloth was dried for 5 minutes at 85 C. and cured for 5 minutes at 140 C.The strength retention of the fabric was good. The weight gain of thefabric was 2.1% and the OR was 6. After 5 launderings the OR was 3 andafter 5 drycleanings the OR was 2. The spray rating was 50 both beforeand after 5 launderings.

Printcloth was treated in the same manner except that a 3% aqueoussolution of FNAPO containing 0.6% zinc fluoborate was used. Similarresults on oil and water repellency and strength retention wereobtained.

Example 13 The two treatments in Example 12 were repeated except thatthe fabric used was treated with dimethylol ethyleneurea to impartwash-wear properties prior to treatment with FNAPO. Similar results onoil and water repellency were obtained. Fabric strength was lower due tothe wash-wear finish.

Example 14 Cotton printcloth was impregnated with an aqueous solutioncontaining 5% FNAPO and 5.5% zinc fluoborate. The fabric was dried for 5minutes at 85 C. and cured for 5 minutes at 150 C. The OR was 6. After 5launderings in a Tergitometer the OR was 2, and after a 3 hourextraction in a Soxhlet extractor the OR was 5.

Example 15 Two printcloth samples were treated as in Example 14 except1% zinc fluoborate .was used and one sample was 8 cured for 3 minutes at160 C., and the other cured for 10 minutes at 160 C. The first samplehad an OR of 5. After 5 launderings in a Tergitometer the OR was 3. Thesecond sample had an original OR of 6, and an OR of 3 after 5launderings in a Tergitometer. The OR of the samples was unaffected byextraction with tetrachloroethylene.

Example 16 Cotton printcloth was impregnated with an aqueous solutioncontaining 10 FNAPO and 1% zinc fluoborate. The fabric was dried for 9minutes at C. and cured for 5 minutes at 160 C. The OR was 6 before andafter extraction with tetrachloroethylene and 4 after five Tergitometerlaunderings.

Example 17 Printcloth was treated as in Example 16 except a 5% solutionof FNAPO was used and the fabric was cured for 30 minutes at C. withoutpredrying. The OR was 6 before and after tetrachloroethylene extraction.

Example 18 A 5% aqueous solution of telomer containing 1% zincfluoborate was prepared and applied to cotton printcloth from a singlebath. The cloth was dried for 5 minutes at 85 C. and cured for 5 minutesat C. The weight gain of the fabric was 3.5% and the OR was 2. After onehome laundering the OR was zero, and after 4 drycleanings the OR was 1.The spray rating was 50 before and after 5 home launderings or Sdrycleanings. The OR was 2 after 3 hours extraction withtetrachloroethylene in a Soxhlet extractor.

We claim:

1. Diethyl 1-iodo-1H,2H,2H perfluorononylphosphonate.

2. Tetraethyl 1-(1H,1Hperfluorooctyl-3-iodo-l,3-trimethylenediphosphonate.

3. Tetraethyl 1-(1H,1H-perfluoro6ctyl)-1,3-trimethylenediphosphonate.

References Cited UNITED STATES PATENTS 2,899,454 8/1959 McBee et a1.260955 FOREIGN PATENTS 1,454,535 10/1966 France 260955 1,122,404 8/ 1968Great Britain 260955 OTHER REFERENCES Moreau et al.: J. of Chem. &Engin. Data, vol. 14, No. 3, July 1969, PP- 403-5.

ANTON H. SUTTO, Primary Examiner U.S. Cl. X.R.

260955, 502.4 R, 502.4 P, 543 P

